Security in Mobile Ad-hoc NETworks (MANET) is difficult to achieve, notably because of the vulnerability of wireless links, the limited physical protection of nodes, the dynamically changing topology, the absence of a certification authority, and the lack of a centralized monitoring or management point. In this paper, the authors embed an efficient asymmetric encryption strategy to protect and ensure anonymity for source routes when employing a source routing protocol. The base protocol used for source routing is DSR and to prevent DoS attack which occurs by modifying source route an onion based asymmetric key approach is embedded.